CA3020006C - Optical scanner for a human or animal tissue cutting device - Google Patents

Abstract

The present technology relates to a cutting-out apparatus to improve the quality of the impact points generated in ocular tissue to be treated; the apparatus comprises a laser beam treatment device, the treatment device comprising: - a shaping system positioned on the trajectory of said beam, the system including a spatial light modulator to modulate the wavefront phase of the laser beam; - an optical focusing system downstream from the shaping system, comprising a concentrator module to focus the phase-modulated laser beam in a focal plane and a depth-positioning module to displace the focal plane into a plurality of cutting-out planes; - a sweeping optical scanner arranged between the concentrator module and the depth-positioning module to displace the pattern in the cutting-out plane in a plurality of positions.

Description

OPTICAL SCANNING SCANNER OF A FABRIC CUTTING DEVICE
HUMAN OR ANIMAL
TECHNICAL AREA
The present invention relates to the technical field of operations surgical carried out with a femtosecond laser, and more particularly that of the ophthalmic surgery in particular for cornea or lens cutting applications.
The invention relates to a device for cutting human or animal tissue, such as a cornea, or lens, using a femtosecond laser.
By femtosecond laser, we mean a light source, capable of emitting a beam LASER in the form of ultra-short pulses, the duration of which is included between 1 femtosecond and 100 picoseconds, preferably between 1 and 1000 femtoseconds, notably of the order of a hundred femtoseconds.
PRIOR ART
It is known from the state of the art to carry out operations eye surgery by means of a femtosecond laser, such as cutting operations of corneas or crystalline.
The femtosecond laser is an instrument capable of cutting tissue corneal by example, by focusing a LASER beam into the stroma of the cornea, and by making a succession of small adjacent cavitation bubbles, which then forms a cutting line.
More precisely, when focusing the LASER beam in the cornea, plasma is generated by non-linear ionization when the laser intensity exceeds a threshold value, called optical breakdown threshold. A cavitation bubble is then formed, generating a very localized disruption of surrounding tissues. Thus, the volume actually ablated by laser is very weak compared to the disrupted zone.
The area cut by the laser with each pulse is very small, of the order micron or of around ten microns depending on the power and focus of the beam.
Thus, a cut corneal lamellar can only be obtained by performing a series of impacts contiguous on the entire surface of the area to be cut.
The movement of the beam can then be carried out by a device for scan, compound controllable galvanometric mirrors, and/or plates allowing the shift optical elements, such as mirrors or lenses. This device scanning allows you to moving the beam in a back and forth path along a succession of segments forming a path of movement of the beam.
To cut a cornea on a surface of 1mm2, it is necessary to make approximately 20,000 impacts very close to each other. Today these impacts are realized one by one one to one speed average of 300,000 impacts/second. To cut a cornea on a surface of approximately 65mm2, taking into account the times during which the laser stops the production of

2 pulses at the end of the segment to allow the mirrors to position themselves on the segment Next, it takes on average 15 seconds. The surgical cutting operation is therefore slow.
To optimize the cutting time, it is known to increase the frequency of the laser.
However, increasing frequency also implies an increase of the speed of movement of the beam, using stages or scanners adapted. He is also known to increase the spacing between laser impacts on the fabric to cut, but generally to the detriment of the quality of the cut.
Most femtosecond lasers for corneal cutting thus use high working frequencies, particularly above 100kHz, associated with systems of movement of the beam combining scanners and movement stages, what strikes the total cost of the installation, and therefore of the surgical operation billed.
To remedy this problem of speed of LASER cutting, it is also known to use galvanometric mirrors to increase cadence, speed, and the journey of LASER beam deflection However, this technique does not give complete satisfaction in terms of results.
Another solution to reduce cutting time consists of generating several bubbles cavitation simultaneously. Documents US 2010/133246, EP 1790 383 and US
2016/067095 describe cutting devices based on the technique of subdivision of a single primary LASER beam into a plurality of LASER beams secondary. These devices generally include an optical system ¨ such as one (or several) beam splitter(s) ¨ to produce secondary LASER beams allowing to each generate a respective cavitation bubble.
The fact of simultaneously generating n cavitation bubbles makes it possible to reduce the duration total cutting by a factor n.
The multiplication of a beam into several beams, with the aim of to accelerate the procedure, has already been described but always by means of purely solutions optical, either by diffraction, or by multiple reflections. The result was never usable in the clinic, mainly because the different beams were not of uniform size.
Furthermore, the subdivision technique induces an increase in the diameter of the plurality of secondary LASER beams in relation to the beam diameter Primary LASER
unique produced by the femtosecond laser. In fact, LASER beams secondary correspond to portions of the single primary LASER beam separated spatially. Due to the non-zero distance between the different beams LASER
secondary, the diameter of the assembly formed by the plurality of beams LASER
secondary is greater than the diameter of the primary LASER beam.
This increase in diameter can be a disadvantage, particularly in the case where the cutting device includes a scanning system ¨ such as a scanner optical ¨ for

3 moving the plurality of secondary LASER beams in a plane of cutting. Indeed, the inlet diameter of a scanning system is generally of the order of diameter of single primary LASER beam so that some beams secondary do not penetrate not in the scanning system.
An aim of the present invention is to provide a cutting device allowing to overcome at least one of the aforementioned drawbacks. In particular, a goal of the present invention is to propose a cutting device making it possible to produce a plan of cut out more quickly than with existing systems and whose cutting quality is improved.
STATEMENT OF THE INVENTION
For this purpose the invention proposes a device for cutting human tissue or animal, such than a cornea, or a lens, said device including a femtosecond laser capable of issuing a LASER beam in the form of pulses and a treatment device of the beam LASER generated by the femtosecond laser, the treatment device being arranged downstream of said femtosecond laser, remarkable in that the treatment device includes: a shaping system positioned on the trajectory of said beam, for modulate the phase of the wavefront of the LASER beam so as to obtain a single beam LASER
modulated in phase according to a modulation instruction calculated to distribute the energy of LASER beam in at least two points of impact forming a pattern in its focal plane, an optical focusing system downstream of the shaping system, the optical system focusing unit comprising a concentrator module for focusing the beam LASER
modulated in phase in a focusing plane and a positioning module in depth to move the plane of focus into a plurality of cutting planes, a optical scanner scanning device arranged between the concentrator module and the positioning in depth to move the pattern in the cutting plane in a plurality of positions.
We mean, in the context of the present invention, by point of impact a area of LASER beam included in its focal plane in which the intensity of said beam LASER is sufficient to generate a cavitation bubble in tissue.
In the context of the present invention, we mean points of impact adjacent, two points of impact arranged facing each other and not separated by another point of impact.
By neighboring points of impact we mean two points of a group of points adjacent between which the distance is minimum.
In the context of the present invention, the term “pattern” means a plurality points LASER impact generated simultaneously in a focusing plane of a beam LASER shaped ¨ that is to say modulated in phase to distribute its energy in several distinct spots in the focusing plane corresponding to the cutting plane of the device.
Thus, the invention makes it possible to modify the intensity profile of the beam LASER in plane cutting, in a way that can improve the quality or the speed of cutting into

4 depending on the chosen profile. This modification of intensity profile is obtained by modulation of the phase of the LASER beam Optical phase modulation is carried out using a phase mask.
Energy of the incident LASER beam is preserved after modulation, and the implementation shape of beam is produced by acting on its wave front. The phase of a wave electromagnetic represents the instantaneous situation of the amplitude of a wave electromagnetic. The sentence depends on both time and space. In the case of formatting spatial of a LASER beam, only variations in phase space are considered.
The wavefront is defined as the surface of the points of a beam having a phase equivalent (ie the surface made up of points whose travel times from the source having emitted the beam are equal). The modification of the spatial phase of a beam passes therefore by the modification of its wave front.
This technique allows the cutting operation to be carried out in a more fast and more efficient because it uses several LASER spots achieving each one a cutout and according to a controlled profile.
In the context of the present invention, the phase modulation of the wavefront allow to generate a single modulated LASER beam which forms several points of impact only in the cutting plane. Thus, the modulated LASER beam is unique throughout along the propagation path. Phase modulation of the wavefront allows to delay or to advance the phase of the different points on the surface of the beam by relation to the front initial wave so that each of these points produces interference constructive in N points distinct in the focal plane of a lens. This redistribution of energy in a plurality of points of impact only take place in a single plane (ie the plane of focus) and not all the way of the propagation path of the modulated LASER beam. On the contrary, the US document 2010/0133246 proposes using an optical system based on phase and allowing to subdividing a primary beam into a plurality of secondary beams having angles of different propagation.
The modulation technique according to the invention (by generation of a unique beam modulated LASER) helps limit the risks of quality degradation of the surface cut out. Indeed, if a portion of the single modulated LASER beam is lost along of the beam propagation path, the intensities of all points impact of the pattern will be attenuated at the same time (conservation of homogeneity between the different points of impact of the pattern) but no point of impact will disappear in the cutting plane. At opposite with the beam subdivision technique proposed in US 2010/0133246, if a portion of the plurality of secondary beams is lost along the path of spread, then certain impact points of the pattern (corresponding to the impact points generated by the beams secondary lost) will be absent in the cutting plane, which degrades noticeably the quality of the cutting carried out.
Preferred but non-limiting aspects of the cutting apparatus are the following:
- the device may further comprise a scanner control unit optical for

5 control the movement of the pattern along a movement path comprising at least one segment in the cutting plane;
- the control unit can be programmed to control the activation of the femtosecond laser so that the distance between two adjacent positions of the pattern along a segment of moving path can be greater than or equal to the diameter of a point impact of pattern ;
- the control unit can be adapted to control the movement of the pattern along a travel path may include a plurality of segments, the distance between two adjacent segments of the path of movement being greater than the dimension of the pattern according to one perpendicular to the direction of movement of the pattern;
- the control unit can be programmed to control the movement of the pattern along of a travel path may include a plurality of segments parallel, the distance between two neighboring segments of the path of movement being constant and lower or equal to 3N times the diameter of a point of impact, where N corresponds to the number points impact of the motif;
- the control unit can be programmed to control the movement of the pattern along of a travel path may include a plurality of segments parallel, the distance between at least two neighboring segments being different from the distance between at least two other neighboring segments;
- the control unit may be able to control the movement of the pattern according to a path of niche-shaped movement in the cutting plane;
- the control unit may be able to control the movement of the pattern according to a path of spiral-shaped movement in the cutting plane;
- the optical scanning scanner may include at least one optical mirror rotating around of at least two axes, the control unit of the optical scanner controlling the mirror pivot so as to move the pattern according to the movement path;
- the device may further comprise at least one Dove prism positioned between the shaping system and optical scanning scanner;
- the control unit can also be programmed to control laser activation femtosecond, the control unit activating the femtosecond laser when the speed of scanning of the optical scanner is greater than a threshold value, - the device may include a filter placed downstream of the placing system fit for block parasitic energy generated in the center of the shaping system,

6 - the filter may comprise a plate including an opaque zone at the LASER radiation arranged in the center of the plate, and a zone transparent to radiation LASER
extending to the periphery of the opaque zone - the formatting system can consist of a set of masks of phase, each mask acting on the phase of the LASER beam to distribute the energy of the beam LASER by phase modulation according to a distinct pattern, the masks being fixed to a routing device, the control unit being programmed to control the device routing (by issuing one or more control signals) in order to move each mask enters:
o an active position in which the mask cuts the optical path of the beam LASER, and o an inactive position in which the mask does not extend over the optical path of the LASER beam - the shaping system can consist of a spatial modulator of light, the unity of control being programmed to control the spatial light modulator by emission of minus one control signal, each control signal inducing the display on the spatial light modulator of a phase mask forming a set point modulation;
- the control unit can be programmed to control the updating system in shape, said control unit being adapted to emit at least first and second signals command (between two respective cutting planes or in the same cutting plane cutting):
o the first control signal inducing the modulation of the phase of the wave front of the LASER beam according to a first modulation instruction calculated for distribute the energy of the LASER beam into a plurality of first points of impact in the focal plane of the shaping system, the first points of impact constituting a first reason, o the second control signal inducing the modulation of the phase of the forehead wave of the LASER beam according to a second modulation instruction calculated to distribute the energy of the LASER beam into a plurality of second points of impact in the focal plane of the shaping system, the second points of impact constituting a second pattern different from the first pattern.
The invention also relates to a method for controlling a cutting device of a human or animal tissue, such as a cornea, or a lens, said device including a laser femtosecond capable of emitting a LASER beam in the form of pulses and a device processing the LASER beam generated by the femtosecond laser, the device treatment being arranged downstream of said femtosecond laser, the method including:
- Shaping the LASER beam to modulate the phase of the forehead beam wave LASER so as to obtain a single phase-modulated LASER beam according to one

7 modulation setpoint calculated to distribute the energy of the LASER beam in at least two points of impact forming a pattern in its focal plane, - Focusing the modulated LASER beam to focus the beam Modulated LASER
in phase in a plane of focus, - The movement of the pattern in the cutting plane in a plurality of positions.
Preferred but non-limiting aspects of the process according to the invention are the following:
- the moving step may consist of moving the pattern along a road of movement comprising at least one segment in the cutting plane, - the method may further comprise a step of activating the laser femtosecond so as the distance between two adjacent positions of the pattern along a segment of the path of displacement is greater than or equal to the diameter of an impact point of the pattern, - the moving step may consist of moving the pattern along a road of displacement comprising a plurality of segments, the distance between two segments adjacent to the movement path being greater than the dimension of the pattern according to one perpendicular to the direction of movement of the pattern, - the moving step may consist of moving the pattern along a road of displacement comprising a plurality of parallel segments, the distance between two neighboring segments of the path of movement being constant and lower or equal to 3N times the diameter of an impact point, where N corresponds to the number of impact points of the pattern, - the moving step may consist of moving the pattern along a road of displacement comprising a plurality of parallel segments, the distance between at least two neighboring segments being different from the distance between at least two others neighboring segments, - the moving step can consist of moving the pattern along a path of displacement in the shape of a niche in the cutting plane, - the movement step can consist of moving the pattern along a path of shift in the shape of a spiral in the cutting plane, - the method may further comprise a step of activating the laser femtosecond, the unit control activating the femtosecond laser when the scanning speed of the to scan optical is greater than a threshold value, - the method may further comprise a step of filtering the beam Modulated LASER
to block parasitic energy generated at the center of a power supply system shape, - the formatting step may include the sub-steps consisting of:
modulate the phase of the wavefront of the LASER beam according to a first instruction of calculated modulation to distribute the energy of the LASER beam into a plurality of first points of impact in the focal plane of the shaping system, the first points of impact constituting a first pattern, and to modulate the phase of the wavefront of the LASER beam according to a second modulation setpoint calculated to distribute the energy of the LASER beam in a plurality

8 second points of impact in the focal plane of the shaping system, the second points of impact constituting a second pattern different from the first pattern, - the modulation setpoint can be a phase mask calculated in using an algorithm iterative based on a Fourier transform.
BRIEF DESCRIPTION OF THE DRAWINGS
Other characteristics and advantages of the invention will become clear of the description which is made below, for information only and in no way restrictive, with reference to appended figures, in which:
- Figure 1 is a schematic representation of an assembly including the cutting device according to the invention;
- Figure 2 illustrates an intensity distribution of a LASER beam in its focal plane;
- Figure 3 illustrates a path for moving a cutting pattern;
- Figure 4 illustrates cutting plans for a volume of fabric to be destroyed ;
- Figures 5 to 9, 11 to 18, and 20 to 22, 24 and 28 illustrate different examples of pattern cutting, - Figures 10, 19, 23 and 25 to 27 illustrate bubble matrices of cavitation.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to an apparatus for cutting human tissue using a laser femtosecond. In the remainder of the description, the invention will be described, as an example, for cutting a cornea from a human or animal eye.
1. Cutting device With reference to Figure 1, an embodiment of the device is illustrated cutting according to the invention. This can be placed between a femtosecond laser 1 and a target to treat 2.
The femtosecond laser 1 is capable of emitting a LASER beam under the shape impulses. For example, laser 1 emits light of 1030 nm of wave length, in the form of 400 femtosecond pulses. Laser 1 has a 20W power and a frequency of 500 kHz.
The target 2 is for example a human or animal tissue to be cut such as a cornea or a crystalline.
The cutting device includes:
- a shaping system 3 positioned on the trajectory of the beam LASER 11 from femtosecond laser 1, - an optical scanning scanner 4 downstream of the shaping system 3, - an optical focusing system 5 downstream of the optical scanning scanner 4.

9 The cutting device also includes a control unit 6 making it possible to control the shaping system 3, the optical scanning scanner 4 and the optical system focus 5.
Shaping system 3 allows you to modulate the phase of the beam LASER 11 from of the femtosecond laser 1 to distribute the energy of the LASER beam into one plurality of points of impact in its focal plane, this plurality of points of impact generated simultaneously defining a pattern.
The optical scanning scanner 4 allows you to direct the LASER beam modulated into phase 31 from shaping system 3 to move the cutting pattern along a User predefined movement path in the plane of focus 21.
The optical focusing system 5 makes it possible to move the plane of focus 21 ¨
corresponding to the cutting plane ¨ of the modulated and deflected LASER beam 41.
Thus, the formatting system 3 makes it possible to simultaneously generate several points impact defining a pattern, the optical scanning scanner 4 makes it possible to move this pattern in the focusing plane 21, and the optical focusing system 5 allows you to move the focusing plane 21 in depth so as to generate cutouts in plans successive defining a volume.
The different elements constituting the cutting device will now be described more in detail with reference to the figures.
2. Elements of the cutting device 2.1. Shaping system The spatial shaping system 3 of the LASER beam makes it possible to vary the wave surface of the LASER beam to obtain separate impact points one of the others in the focal plane. More specifically, the formatting system 3 allows you to modulate the phase of the LASER beam 11 coming from the femtosecond laser 1 so as to get a unique LASER beam modulated in phase according to a calculated modulation instruction to form intensity peaks in the focal plane of the beam, each intensity peak producing a point respective impact in the focal plane corresponding to the cutting plane.
Having a single modulated LASER beam facilitates the integration of a scanning system ¨ such as an optical scanner ¨ for moving the plurality of beams Secondary LASERs in a cutting plane. In fact, the inlet diameter of a system scanning being of the order of the diameter of the initial LASER beam, the use of a unique modulated LASER beam (whose diameter is substantially equal to the diameter of the beam initial LASER) limits the risks of aberration that can occur with the technique of beam subdivision as described in US 2010/0133246.
The shaping system 3 is, according to the illustrated embodiment, a spatial modulator of liquid crystal light, known by the acronym SLM, from the English acronym Spatial Light 'o Modulator. The inventors have in fact discovered that the use of an SLM
was advantageous despite the teachings of the prior art which dissuade those skilled in the art to use such device (see in particular paragraph [0024] of document US 2015/0164689).
The SLM makes it possible to modulate the final energy distribution of the beam LASER, particularly in the focal plane 21 corresponding to the cutting plane of the fabric 2.
More precisely, the SLM is adapted to modify the spatial profile of the wavefront of the beam Primary LASER 11 from femtosecond laser 1 to distribute energy of the beam LASER in different focusing spots in the focusing plane.
This device allows to limit the costs associated with wavefront phase modulation and thus resolves the issues related to the industrialization of the proposed solution. There phase modulation of wave front can be seen as an interference phenomenon in two dimensions. Each portion of the initial LASER beam coming from the source is delayed or progress compared to initial wave front so that each of these portions is redirected so to carry out a constructive interference at N distinct points in the focal plane of a lens. This redistribution of energy into a plurality of points of impact takes place only in a single plan (ie the plane of focus) and not all along the propagation path of the LASER beam module. Thus, the observation of the modulated LASER beam before or after the plan of focusing does not make it possible to identify a redistribution of energy in one plurality of points of distinct impacts, due to this phenomenon which can be assimilated to interference constructive (which only take place in one plane and not throughout the spread like in the case of splitting an initial LASER beam into a plurality of beams secondary LASER).
To better understand this phenomenon of wavefront phase modulation, we has schematically illustrated in Figure 2 of the intensity profiles 32a-32e obtained for three examples of distinct optical assemblies. As shown in Figure 2, a beam LASER 11 emitted by a laser source 1 produces an intensity peak 32a of Gaussian form at a point of impact 33a in a focusing plane 21. The insertion of a separator beam 7 between source 1 and focusing plane 21 induces the generation of a plurality of secondary LASER beam 71, each secondary LASER beam 71 producing a respective point of impact 33b, 33c in the focusing plane 21 of the LASER beams secondary 71. Finally, the insertion between source 1 and the plane of focus 21 of an SLM 3 programmed using a phase mask forming an induced modulation setpoint there modulation of the phase of the wavefront of the LASER beam 11 coming from the source 1. The LASER 31 beam whose wavefront phase has been modulated allows to induce the production of several spatially separated 33d, 33e intensity peaks in the focal plane 21 of the LASER beam, each peak 32d, 32e corresponding to a point of impact 33d, 33e respective making a cut. The phase modulation technique of the wave front allows you to generate several simultaneous cavitation bubbles without beam reduction Initial LASER produced by femtosecond laser 1.
The SLM is a device consisting of a layer of liquid crystals controlled orientation making it possible to dynamically shape the wave front, and therefore the beam phase LASER The liquid crystal layer of an SLM is organized like a grid (or matrix) of pixels. The optical thickness of each pixel is controlled electrically by orientation of liquid crystal molecules belonging to the surface corresponding to the pixel.
The SLM (9) exploits the principle of anisotropy of liquid crystals, i.e.
say the change of the index of liquid crystals, depending on their spatial orientation.
The orientation of Liquid crystals can be made using an electric field. Thus, the modification of the liquid crystal index modifies the wavefront of the LASER beam (4).
In a known manner, the SLM implements a phase mask, that is to say a map determining how the phase of the beam must be changed to obtain a distribution of given amplitude in its plane of focus. The phase mask is a picture two-dimensional, each point of which is associated with a respective pixel of the SLM. This mask of phase makes it possible to control the index of each liquid crystal of the SLM in converting the value associated with each point of the mask ¨ represented in gray levels included between 0 and 255 (therefore from black to white) ¨ in one command value ¨ represented in one phase included between 0 and 2Tr. Thus, the phase mask is a modulation instruction displayed on the SLM
to cause an unequal spatial phase shift of the LASER beam in reflection (4) illuminating the SLM. Of course, those skilled in the art will appreciate that the level range of gray may vary depending on the SLM model used. For example in some cases, the beach level of gray can be between 0 and 220. The phase mask is generally calculated by:
- an iterative algorithm based on the Fourier transform, such as type algorithm IFTA, acronym for the Anglo-Saxon expression Iterative Fourrier Transform Algorithm, or by - various optimization algorithms, such as genetic algorithms, or simulated annealing.
This makes it possible to control homogeneity, intensity, quality and shape.
some issues impact points generated in the cutting plane.
Different phase masks can be applied to the SLM depending on the number and the position of the desired points of impact in the focal plane of the beam LASER In all cases, the person skilled in the art knows how to calculate a value at each point of the mask phase for distribute the energy of the LASER beam in different spots of focus in the plane of focal.
The SLM therefore allows, from a Gaussian LASER beam generating a single point of impact, and by means of the phase mask, to distribute its energy by phase modulation so as to simultaneously generate several points of impact in its plan of focus on from a single LASER beam shaped by phase modulation (single beam upstream and downstream of the SLM).
In addition to a reduction in corneal cutting time, the technique of modulation of the phase of the LASER beam according to the invention allows other improvements, such as better surface quality after cutting or a reduction in the mortality endothelial. The different points of impact of the pattern can, for example, be regularly spaced on both dimensions of the focal plane of the LASER beam, way to form a grid of LASER spots Thus, the shaping system 3 makes it possible to carry out a shaping operation.
cutout surgical procedure in a rapid and efficient manner. SLM makes it possible to shape a manner dynamic the wavefront of the LASER beam since it is configurable numerically.
This modulation allows the shaping of the LASER beam in a way dynamic and reconfigurable.
The SLM can be configured to shape the beam wavefront LASER
any other way. For example, each point of impact may present a shape any geometric, other than circular (for example ellipse, etc.).
This can present certain advantages depending on the application considered, such as a increase in speed and/or quality of cutting.
2.2. Optical scanning scanner The 4 scanning optical scanner allows the LASER beam to be deflected phase modulated 31 so as to move the pattern 8 into a plurality of positions 43a-43c in the plan of focusing 21 corresponding to the cutting plane.
The 4 scanning optical scanner includes:
- an entry port to receive the phase-modulated LASER beam 31 from the unit formatting 3, - one (or more) optical mirror(s) pivoting around at least two axes to deflect the LASER beam modulated in phase 31, and - an outlet orifice to send the deflected modulated LASER beam 41 to the system focusing optics 5.
The optical scanner 4 used is for example an IntelliScan scanning head III of the company SCANLAB AG.
The entry and exit orifices of such an optical scanner 4 have a order diameter from 10 to 20 millimeters, and the achievable scanning speeds are the order of 1m/s to 10m/s.
The mirror(s) is (are) connected to a motor(s) to allow them pivoting. This motor(s) for pivoting the mirror(s) is (are) advantageously controlled by the unit of the control unit 6 which will be described in more detail in the following.
The control unit 6 is programmed to control the optical scanner of scan 4 of so as to move the pattern 8 along a movement path 42 contained in the plan of focus 21. In some embodiments, the path of movement 42 includes a plurality of cutting segments 42a-42c. The movement path 42 can advantageously present a niche shape. In this case, if the scanner optical 4 begins a first cutting segment 42a from the left, it will begin on second segment cutting segment 42b from the right, then the third cutting segment 42c from the left, then the next segment to the right and so on all the way to movement 42 of the pattern 8. This speeds up the cutting of the fabric avoiding the need for optical scanner 4 to reposition the pattern 8 at the start of each cutting segment 42a-42c successive.
To further accelerate the cutting operation in the focusing plane 21, the path of displacement 42 can advantageously have a spiral shape. This allows maintain the scanning speed of the optical scanner 4 constant throughout the cutting plane.
Indeed, in the case of a movement path 42 in the form of a slot, the optical scanner 4 must stop at the end of each cutting segment 42a to move on the segment cutting according to 42b, which consumes time.
The scanning of the beam has an influence on the cutting result obtained.
In fact, the scanning speed used, as well as the scanning step, are parameters influencing the quality of the cut.
Preferably, the scanning step ¨ corresponding to the distance between two adjacent positions 43a, 43b of pattern 8 along a segment of the path of displacement 42 ¨ is chosen greater than or equal to the diameter of an impact point 81 of pattern 8.
This allows to limit the risks of superposition of points of impact during shots successive.
Also, when the movement path 42 has a niche shape, there distance ec between two adjacent segments 42a, 42b of the path of displacement 42 is preferably chosen greater than the dimension of the pattern 8 according to a perpendicular to its direction of movement. This also makes it possible to limit the risks of superposition of points impact 81 during successive shots.
Finally, to limit the duration of the cutting operation in the plane of cutting, while guaranteeing a certain quality of the cut, the distance between two adjacent segments 42a, 42b of the movement path 42 can be chosen equal to a maximum (and of lower preference) of 3N times the diameter of an impact point 81, where N is number of impact points of pattern 8.
In one embodiment, the cutting apparatus further comprises a prism by Dove.
This is advantageously positioned between the shaping system 3 and the scanner scanning optics 4. The Dove prism makes it possible to implement a pattern rotation 8 which can be useful in certain applications or to limit the size of the boot zone of each cutting segment 42a-42c.
Advantageously, the control unit 6 can be programmed to activate the laser femtosecond 1 when the scanning speed of the optical scanner 4 is greater than a threshold value.
This makes it possible to synchronize the emission of the LASER 11 beam with the scan of the optical scanning scanner 4. More precisely, the control unit 6 activates the laser femtosecond 1 when the pivoting speed of the mirror(s) of the optical scanner 4 is constant. This makes it possible to improve the cutting quality by carrying out a surfacing homogeneous of the cutting plane.
2.3. Optical focusing system The optical focusing system 5 makes it possible to move the plane of focus 21 of modulated and deflected LASER beam 41 in a cutting plane of the fabric 2 desired by the user.
The optical focusing system 5 comprises:
- an entry port to receive the phase-modulated LASER beam and deviated from optical scanning scanner, - one (or more) motorized lens(es) to allow its (their) moving in translation along the optical path of the phase-modulated LASER beam and deviated, and - an exit orifice to send the focused LASER beam towards the tissue to be treated.
The lens(es) used with the optical focusing system 5 can be f-theta lenses or telecentric lenses. F-theta lenses and telecentrics allow to obtain a plane of focus over the entire XY field, unlike standard lenses for which it is curved. This ensures a beam size constant focused over the entire field. For f-theta lenses, the beam position is directly proportional to the angle applied by the scanner while the beam is always normal the sample for telecentric lenses.
The control unit 6 is programmed to control the movement of the (or of the) lens(es) of the optical focusing system 5 along an optical path of the beam LASER so as to move the focusing plane 21 in at least three cutting plans respective 22a-22e so as to form a stack of cutting planes of the fabric 2. This allows you to make a cut in a volume 23, for example in the frame of a surgery refractive.
The control unit 6 is capable of controlling the movement of the optical system of focusing 5 to move the focusing plane 21 between a first extreme position 22a and a second extreme position 22nd, in that order. Advantageously, the second extreme position 22nd is closer to femtosecond laser 1 than the first position extreme 22a.
Thus, the cutting planes 22a-22e are formed starting with the plane of cutout the deepest 22a in the fabric and stacking the cutting planes successive until the plan 5 of the most superficial cutting 22nd in the fabric 2. This avoids the problems associated with penetration of the LASER beam into the tissue 2. In fact, the bubbles of cavitation form an opaque bubble barrier (known as OBL, acronym for the English expression Opaque Bubble Layer) preventing the propagation of energy from the beam LASER
under these. It is therefore preferable to start by generating the bubbles of cavitation

10 deeper as a priority in order to improve the efficiency of the device cutting.
Preferably, the length of the optical path between the shaping system 3 and the 5 focusing optical system is less than 2 meters, and even more preferably less than 1 meter. This makes it possible to limit power losses due to energy dispersed on the optical path. In fact, the greater the distance between the system formatting 15 3 and the optical focusing system 5 is greater, the greater the loss of power on the ride is important.
Advantageously, the control unit 6 can be programmed to vary the form of pattern 8 between two cutting planes 22a-22b (or 22b-22c, or 22c-22d, or 22d-22nd) successive. Indeed, when cutting into a volume 23, it can be better to increase the precision of the cutting in the peripheral cutting planes 22a, 22e and to increase the cutting speed in the intermediate cutting planes 22b, 22c, 22d located between the peripheral cutting planes 22a, 22e. For example in the case of cutting of a volume 23 composed of a stack of five cutting planes 22a-22e, the unit of order 6 can control the formatting system 3 by transmitting to it:
- a first phase mask corresponding to a first pattern allowing to increase the cutting precision when the focus plane corresponds to the first and fifth cutting plans 22a and 22e, - a second phase mask when the focusing plane corresponds to the second, third and fourth cutting planes 22b-22d.
Likewise, the control unit 6 can be programmed to vary the pitch dist from optical scanning scanner 4 and/or the shape of the cut area (by modifying the path of movement of the pattern) between two respective cutting planes. this allows also either to increase the precision of cutting, i.e. the speed of cutting in a cutting plane to another.
Finally, the control unit 6 can be programmed to control the scanner optics of scanning 4 so as to vary the area cut out in the plane of focus 21 between two WO 2017/1747

11 PCT/EP2017/058225 successive cutting planes 22d, 22e. This allows you to vary the shape of the volume 23 finally divided according to the intended application.
Preferably, the distance between two successive cutting planes is included between 2 pm and 500 pm, and in particular:
- between 2 and 20pm to process a volume requiring high precision, for example example in refractive surgery, preferably with a spacing between 5 and lOpm, or - between 20 and 500pm to treat a volume not requiring a large precision, like for example to destroy the central part of a lens nucleus, with preferably one spacing between 50 and 200pm.
Of course, this distance can vary in a volume 23 composed of a stack of cutting plans 22a-22e.
2.4. Filtered The cutting device may also include a filter placed downstream of the system of formatting 3.
The filter allows on the one hand to block the parasitic energy generated at center of the system formatting 3 (a phenomenon known as zero order). In effect, when phase modulation of the LASER beam with the adjustment system form, part of the LASER beam coming from the laser source 1 is not modulated (due to the existing space between the pixels of the liquid crystals of the SLM). This part of the beam Unmodulated LASER
can induce the generation of an energy peak forming at the center of the SLM.
The filter also makes it possible to limit the risks of LASER lesions.
unexpected for the patient in the event of a failure of the shaping system 3. Indeed, if the betting system in form 3 is defective, the LASER beam is not modulated, which induces training of a very strong energy peak at the center of the shaping system 3. In blocking this peak of very high energy, the filter prevents the untimely generation of cavitation bubbles.
The filter can be placed between two converging lenses arranged downstream of the system of formatting 3. Indeed, order 0 can only be eliminated in a plan of Fourier (this is say at the focus of a lens), where beam shaping occurs.
The filter consists, for example, of a plate transparent to radiation LASER on its entire surface with the exception of a central region of the plate which is opaque to LASER radiation To make the central region of the plate opaque to radiation LASER, the filter may include an opaque pellet placed in the center of the surface, the pellet having a diameter greater than or equal to the diameter of a beam LASER
This filter is then positioned so that a straight line normal to the system of formatting 3, and passing through the center of said shaping system 3 also passes by the region central opaque to LASER radiation 2.5. Control unit As indicated previously, the control unit 6 makes it possible to control the different elements constituting the cutting device, namely the laser femtosecond 1, the shaping system 3, optical scanning scanner 4 and system optics of focus 5.
The control unit 6 is connected to these different elements by through one (or several) communication bus allowing:
- the transmission of control signals such as = the phase mask to the shaping system, = the femtosecond laser activation signal, = the scanning speed of the optical scanning scanner, = the position of the optical scanning scanner along the scanning path shift, = the depth of cut to the optical focusing system.
-receiving measurement data from the different elements of the system such as = the scanning speed achieved by the optical scanner, or = the position of the optical focusing system, etc.
The control unit 6 may be composed of one (or more) control station(s).
work, and/or of one (or more) computer(s) or may be of any other type known to the skilled person.
The control unit 6 can for example include a mobile telephone, a Tablet electronic (such as an IPADC), a personal assistant (or PDA, acronym for the expression Anglo-Saxon Personal Digital Assistant), etc. In any case, the unit order 6 includes a processor programmed to enable laser control femtosecond 1, from shaping system 3, optical scanning scanner 4, system optics of focus 5, etc.
2.6. Pattern The reconfigurable modulation of the wavefront of the LASER beam makes it possible to generate multiple simultaneous points of impact 81 each having a size and a controlled position in the plane of focus 21.
These different points of impact 81 form a pattern 8 in the focal plane 21 of the beam LASER modulated.
The number of impact points 81 of pattern 8 decreases the time by the same number of times necessary to the surgical cutting operation.
However, the dimension of the pattern 8, the number of points of impact 81 that it understands and their respective positions relative to the direction of movement are features techniques chosen judiciously to meet technical constraints associated with cutting fabric, as will become apparent later.
2.6.1. Constraints and chosen solutions 2.6.1.1. Maximum number of impact points per pattern In order to speed up the cutting of fabric 2, it is preferable to have a pattern 8 including a maximum number of impact points 81. In ophthalmic laser systems current, the energy per pulse and per spot required for corneal cutting is the order of 1pJ.
Thus, with a femtosecond laser ¨ such as a Satsuma laser source (Marketed by System Amplitude) ¨ providing a power of 20W at a rate of 500kHz, either at maximum energy of 40pJ/pulse, it is theoretically possible to create a pattern 8 composed of 40 identical 81 impact points.
However, in any laser system, losses occur along the path optical. So, in a prototype tested by the Applicant, the power arriving on the cornea was no longer only 12W for shaping six impact points 81 of overall size (30pm*22pm). THE
focused beam diameter was 8pm in diameter, compared to around 4pm at maximum for current ophthalmic lasers. As part of a prototype tested by the Applicant, 4 times more energy per spot was necessary compared to lasers current ophthalmics, i.e. 4pJ. So for this prototype, it was chosen to use a pattern composed of six impact points 81 (maximum). Of course, if the power laser femtosecond 1 is greater, the pattern 8 can include a number of points impact 81 greater than six.
2.6.1.2. Distribution of impact points in the pattern The six points of impact 81 of pattern 8 can be distributed according to different configurations.
For example the six points of impact 81 can be distributed along a single line. There total length of pattern 8 is then equal to the sum between the diameter of a point of impact 81 and the center-to-center distance between the extreme points of impact 81 of the pattern 8. The width of the pattern 8 is for its part equal to the diameter of a point of impact 81.
As indicated previously, shaping the LASER beam results in a loss of power, due to energy dispersed on the optical path. The size overall stake in shape (and therefore the size of the pattern 8) is one of the factors influencing this loss of energy.
The larger the size (in length or width) of pattern 8, the greater the power loss is tall. A distribution of six points of impact 81 on a single line therefore induces a loss significant power.
For information :
- a pattern 8 of size 30pm*22pm including six impact points 81 leads a loss of power of approximately 10%, while - a pattern 8 of size 84pm*20pm including five impact points 81 leads to a loss of power of approximately 25%.
Thus, for a given number of impact points 81, the compact patterns (report of sizes in length and width close to 1) lead to a loss of energy weaker.

This is why the points of impact 81 of pattern 8 are preferably included in surface whose ratio between length and width is between 1 and 4, preferably between 1 and 2, and even more preferably between 1 and 1.5.
For example, the six points of impact 81a-81f of the pattern can be distributed on firsts and second parallel lines 82, 83:
- the first line 82 passing through three points of impact 81a-81c forming a first triplet, and - the second line 83 passing through three other points of impact 81d-81f forming a second triplet distinct from the first triplet.
A pattern corresponding to this distribution is shown in Figure 5.
Advantageously, the impact points 81a-81f of the pattern can be shifted from one line to another depending on direction of displacement D. More precisely, the points of impact 81a-81c of the first triplet can be shifted by a non-zero distance (according to the direction of movement D) relative to points of impact 81d-81f of the second triplet. This makes it possible to avoid the bubble overlay cavitation in the cutting plane during the movement of the pattern 8 by the optical scanner scan 4.
2.6.1.3. Minimum distance between points of impact of the pattern In addition to the distribution of impact points 81 of pattern 8, another parameter of the pattern concerns the distance between adjacent points of impact.
This distance is defined by constraints linked to the implementation system.
shape.
During the operation of shaping the LASER beam from the laser femtosecond, points of impact that are too close interfere with each other due to the spatial coherence of the source. These interferences degrade the shape of the points of impact and make impossible control of the laser intensity level on each point of impact. It is therefore preferable than the distance between adjacent points of impact of the pattern is sufficient to limit this phenomenon interference between too close points of impact.
This sufficient distance depends on the focusing of the beam. The more beam will be focused, the lower this distance will be. Conversely, the less the beam will be focused, the more this distance will be significant.
Taking into account the working distance constraints linked to applications of surgery of the anterior segment of the eye, reproducibility of the implementation shape as well as aberrations of the optical system degrading the spatial coherence of the beam, the limit of separation of two spots is located at approximately lOpm.
This is why the sufficient center-to-center distance between two points of impact adjacent is greater than 5pm, preferably greater than 10pm and even more preferably between 10 p.m. and 8 p.m., particularly between 10 p.m. and 3 p.m.
2.6.1.4. Orientation of the pattern relative to the direction of movement The basic shape shown in Figure 5 can be oriented in different ways ways in the mesh.
The most obvious orientation of this basic form for those skilled in the art is illustrated at Figure 6. This orientation consists of moving the pattern according to a direction of movement 5 D perpendicular to the two lines 82, 83 defined by the first and second triplets of points of impact 81a-81c and 81d-81f.
However, several limitations related to the formatting system and the direction of moving the pattern prevents the use of such an orientation.
As described previously, the distance between two adjacent points of impact 81a, 81b 10 of the pattern is preferably greater than 10 pm. By moving the pattern according to one direction of movement perpendicular to the two lines 82, 83 defined by the first and second triplets of impact points 81a-81c, 81d-81f, the distance between the bubbles of cavitations generated on adjacent segments 42a, 42b parallel to the direction of movement of the pattern will be around 3 p.m.
15 However, a classic distance between adjacent cavitation bubbles for cutting a cornea is of the order of 2pm to 7pm, in particular equal to 5pm.
It is therefore necessary to tilt the pattern 8 so that the bubbles of neighboring cavitations generated on adjacent segments 42a, 42b parallel to the direction of displacement D of pattern 8 are spaced at a distance substantially equal to 5 pm in the direction of 20 displacement.
Note that on the same segment 42a, the distance of 5pm between two bubbles of adjacent cavitations can be obtained by adjusting the movement step of the optical scanner scanning 4.
2.6.2. Examples of reasons retained With reference to Figures 7 to 9, different examples of patterns have been illustrated usable with the cutting device according to the invention.
In the embodiment illustrated in Figure 7, the pattern comprises three points of impact 81a-81c extending along a line 82 of pattern 8. The points of impact are spaced one distance d according to the direction of movement D. The line of the pattern is inclined at an angle a relative to the direction of movement D of the optical scanning scanner 4 of a kind that the cavitation bubbles follow a straight line perpendicular to the direction displacement D
are spaced by a distance e in the cutting plane. We then have the following relationship between the different distances d and e, and the angle of inclination a :
Oc = tan-1 (¨e) d Preferably, the angle of inclination a of the pattern is between 100 and 80.

In the embodiment illustrated in Figure 8, the pattern includes four points of impact 81a-81d extending along two parallel lines 82, 83 of pattern 8:
- A first pair of points of impact 81a, 81b extends along a first line 82 of pattern, - A second pair of points of impact 81c, 81d extends along a second line 83 of the pattern.
This pattern has the shape of a square inclined at an angle of inclination a compared to the direction of movement of the scanning optical scanner. We have the relationship next :
Oc = tan-1 (¨e) d With :
- has the angle of inclination of each line of the pattern relative to the direction of shift, - d corresponding to the distance between two adjacent points of impact, And - e corresponding to the distance between two adjacent points of impact according to one direction perpendicular to the direction of movement of the pattern.
In the embodiment illustrated in Figure 9, the pattern includes six points of impact 81a-81f extending along two parallel lines of pattern 8:
- A first triplet of impact points extends along a first pattern line, - A second triplet of impact points extends along a second line of the pattern.
This pattern has the shape of a rectangle inclined with an angle of inclination a compared with to the direction of movement of the scanning optical scanner. We have the relationship next :
OC = tan-1 (¨e) d With :
- has the angle of inclination of each line of the pattern relative to the direction of shift, - d corresponding to the distance between two adjacent points of impact, summer corresponding to the distance between two adjacent points of impact according to a direction perpendicular to the direction of movement of the pattern.
2.6.3. Theory of determining motives In the following, we will describe an approach implemented by the Applicant For determine possible shapes of impact point patterns allowing to ultimately obtain a arrangement of cavitation bubbles composed of a regular matrix repetitive:
- either in square, - either in an equilateral triangle, while respecting the minimum spacing between adjacent points of impact for limit the interference phenomenon described previously.
There are a variety of possible patterns to obtain by projection when their movement a homogeneous and repetitive matrix of cavitation bubbles 5pm apart some of the others, over the entire treated surface. But there is also a matrix ideal whose points impact points are sufficiently far apart to avoid interference, and close enough so that the total surface of the pattern is small and fits into a field restricted, which is preferable due to the limited size of the optics and mirrors which are found on the way of the LASER beam We proceeded simply by observing an arrangement of spots, either with a square matrix, or with an equilateral triangle matrix, and we we determined the possible patterns to obtain this arrangement, once the pattern is put into movement by the scanning optical scanner.
2.6.3.1. Searching for a pattern to obtain an arrangement of bubbles cavitation in equilateral triangle matrix In Figure 10 illustrating a cut-out plane including a plurality of bubbles cavitation 100, we can observe an arrangement of bubbles in an equilateral triangle forming matrix 101.
Observation leads us to identify several possible reasons, which register in this matrix, as illustrated in Figures 11a to 11c.
In practice none of the three matrices presented above can be used.
Indeed, if the distance separating 2 bubbles from the cut surface is D, or 5pm, it is also necessary to avoid the interference that the minimum distance between 2 points of impact of the pattern is equal to 10pm, i.e.
at least 2D.
Now in the three examples of patterns illustrated in Figures 11a to 11c, there is always at least two points of impact of the pattern too close to each other (distance = D *
(Cos(30)*2) =
1.73 * D. That is, for D = 5 pm, a distance of 8.65 pm (see figure 12).
These observations therefore lead us to define a pattern whose all points of impact are at least 2 * D apart from each other and which makes it possible to obtain the arrangement in Equilateral triangle pattern.
A first example of a pattern is illustrated in Figures 13 to 15, in which all dots are distant from each other at least 2 * D, i.e. for the distances A and B if D =
5pm:
= A = D * cos (30) * 4 = 17 pm = B = \/(2.5D)2 + (cos(300) * D)2 = 13.22 pm On the other hand, the distance between the two most spaced points of the matrix is of C = \/(4.5D)2 + (cos(300) * 5D)2 = 31.22 lim Finally, on this matrix, a precise angulation (see figure 15) makes it possible to reproduce the pattern regular equilateral triangle, and the angles relative to the horizontal and the vertical are:
A= D * cos(30)* 4 B = ,j(2.5D)2+ (cos(30) * D)2 C = il(4.5D)2+(cos(300)*5D)2 a = 19.1 13 = 16.10 A second example of pattern is illustrated in Figures 16 to 18, in which all points are distant from each other at least 2 * D, i.e. for the distances A if D = 5pm:
= A = \/(2.5D)2 + (cos(300) *
D)2 = 1 3, 2 2 -um.
On the other hand, the distance between the two most spaced points of the matrix is of C = \/(5.5D)2 + (cos(300) * 5D)2 = 35 m Finally, on this pattern, a precise angulation makes it possible to reproduce the matrix in triangle equilateral, and the angles relative to the horizontal and vertical are:
A = (2.5D)2 +(cos(30) * D)2 C = (5.5D)2+(cos(300)*5E)2 a = 19.1 13 = 1640 From the above, we have just demonstrated that two different motives could be used to obtain, after setting in motion, an arrangement of bubbles regular arranged in an equilateral triangle matrix.
The choice between the first or the second reason would rather go in favor of first, because the maximum spacing between the 2 most distant points is 31.22 pm at place of 35pm, therefore a more compact shape.
Another advantage of these patterns is that the number of points can be increased to more than 6 (2 X 3 points) by adding new rows of points, respecting the same distances and angulations and moving on to patterns of 9 (3 X 3) or 12 points (3 more.
2.6.3.2. Searching for a pattern to obtain an arrangement of bubbles square matrix cavitation In Figure 19 illustrating a cut-out plane including a plurality of bubbles cavitation 100, we can observe a square arrangement of bubbles forming matrix 101.
Observation leads us to identify a possible pattern, which is part of this matrix, and which respects the minimum spacing between 2 points equal to 2 times the distance D:
= A = aD2 = 14.14 pm = B = \/5D2 = 11.18 pm = E = 3D = 15 pm.
On the other hand, the distance between the two most spaced points of the pattern is of :
C = \/41D2 = 32 1.1m Finally, on this matrix, a precise angulation makes it possible to reproduce the pattern regular in square, and the angle relative to the horizontal is a=26.56.
2.6.3.3. Special case of interlaced patterns We have described the principle of using laser spot patterns to obtain a homogeneous arrangement of cavitation bubbles in the treated tissue. These reasons present a particular arrangement of laser spots, the arrangement of which one by relation to others, and the distances which separate them make it possible to respect the constraints explained above, and in particular the minimum distance between each spot to avoid interference, and distance maximum between each point of impact to obtain cutting quality of the fabric satisfactory. The patterns presented so far all have the particularity to allow when a movement is applied to them by the scan printed by the scanner, to cover uniformly and regularly a surface of cavitation bubbles equidistant, without leave areas untreated. At the end of a segment presenting an arrangement regular points of impact, as indicated in Figure 23, the scanner controls the movement of the matrix of a step 106 equal to the distance between the rows of most impacts distant 104, increased by the distance between two contiguous lines 105.
A variant of the pattern presented in Figure 24 allows you to imagine leaving a untreated area ZNT as presented in Figure 25, this ZNT zone can be treated by the next scan with an arrangement of intertwined impact points. For this the printed step by the scanner between two successive segments is not constant and will be every other time equal to twice the distance between two contiguous rows of impacts 107, and every other time equal to the distance between the most distant rows of impacts 108, increased by the distance between two contiguous lines 105.
2.6.3.4. Special case of a pattern with a central point of impact With reference to Figure 28, another example of a pattern that can be be used for cut out a fabric. This pattern includes a plurality (ie at least three) of points of impact peripherals 81P, and a central point of impact 81B positioned at the barycenter of the pattern, Particularly in the example illustrated in Figure 28, at the intersection between axes diagonals passing through opposite peripheral points of impact.
The presence of this central point of impact makes it possible to take advantage of the phenomena of generation of energy at the center of the pattern (phenomenon known as denomination order 5 zero ). Indeed, during phase modulation of the LASER 11 beam with the system shaping 3, part of the LASER beam coming from the laser femtosecond is not modulated (due to the space existing between the pixels of the liquid crystals of the SLM). This part of the unmodulated LASER beam can induce the generation of a peak of energy forming in center of the SLM.
10 When the pattern does not include a point of impact at this barycenter, it is necessary to limit this zero order energy peak to avoid the generation untimely cavitation bubbles when moving the pattern in the cutting plane.
2.6.3.5. Remarks We have described how to arrange the points of impact of a laser beam multipoint, for 15 that the bubbles generated present a homogeneous and regular arrangement on the surface of cutting fabric. Among an infinity of non-regular arrangements, which can also be used, we demonstrated that to obtain a regular arrangement in equilateral triangle, there were two preferred types of patterns and that to achieve an arrangement regular in square, there was a preferred pattern. For all preferred matrices, the spacings and angles between 20 each point of the matrix were calculated.
Obviously, the invention also relates to any type of pattern whose points of impact are sufficiently spaced from each other to avoid interference and whose movement makes it possible to obtain relatively homogeneous coverage by projection of the surface to be cut, even without regular repetition of a geometric matrix, even if the 25 matrices presented give better results.
The disadvantage of this type of pattern shapes is the introduction of an area priming 102 on the periphery of a regular zone 103. In this initiation zone 102, the cutting is incomplete, as shown in Figure 22. Although the size of this area priming 102 is very small compared to the overall size of the cut (less than 0.5%
with a diameter of corneal hood of 8mm for the examples presented), this priming zone 102 must preferably be as short as possible.
2.6.4. Pattern-related cutting device and associated method In summarizing the previous paragraphs concerning the different features relating to the pattern, the inventors have proposed a device for cutting a human tissue or animal, such as a cornea, or a lens, the device including a laser femtosecond suitable for emit a LASER beam in the form of pulses, and a device for treatment arranged downstream of the femtosecond laser to process the LASER beam generated by the laser femtosecond, the processing device comprising:
- a shaping system 3 positioned on the trajectory of said beam, to modulate the phase of the wavefront of the LASER beam so as to obtain a beam Modulated LASER
in phase according to a modulation instruction calculated to distribute the energy of the beam LASER in at least two points of impact 81 forming a pattern 8 in its focal plane 21 corresponding to a cutting plane, each point of impact carrying out a cutting, - an optical scanning scanner 4 placed downstream of the implementation system form for move the pattern in the cutting plane in a plurality of positions 43 according to one direction displacement D, - a control unit including a processor programmed to allow the piloting of femtosecond laser, shaping system and optical scanner sweep in order to tilt the pattern relative to the direction of movement so that at minus two points impact of the pattern are spaced:
- a non-zero distance along a first axis parallel to the direction of displacement on the one hand, and - a non-zero distance along a second axis perpendicular to the direction of movement on the other hand.
Advantageously, the pattern can comprise at least two (notably three) points adjacent impact points extending along a line of the pattern, the angle between said line of the pattern and the direction of movement being between 10 and 80, preferably between 15 and 40, and even more preferably between 19 and 30. Moreover, the pattern can to understand :
- a first set of at least two (notably three) points of impact arranged along a first line of the pattern, and - a second set of at least two (notably three) other points impact arranged along a second line of the pattern parallel to the first line.
The pattern may further comprise at least one other set of points impact arranged along at least one other line of the pattern, parallel to the first and second lines. THE
points of impact of the second set can be offset by a distance not void by compared to the points of impact of the first set. Alternatively, each point impact of second set can be aligned with a respective point of impact of the first together along a straight line perpendicular to the direction of movement.
Advantageously, the distance between two adjacent points of impact of the pattern may be greater than 5pm preferably greater than Opm and even more preferably between 10 and 15pm.
The pattern can also be inscribed in a surface whose ratio between the length and the width is between 1 and 4, preferably between 1 and 2, and even more preferably between 1 and 1.5. Finally, the pattern may include a central point of impact positioned at the barycenter of pattern.
The inventors have also proposed a method of controlling a device cutout including a femtosecond laser capable of emitting a LASER beam under shape pulses, and a processing device arranged downstream of the laser femtosecond to treat the LASER beam, the treatment device comprising a system of formatting and a scanning optical scanner, the method comprising the steps of :
- modulate, using the shaping system, the phase of the forehead beam wave LASER so as to obtain a LASER beam modulated in phase according to a instructions for modulation calculated to distribute the energy of the LASER beam into at least two points impact 81 forming a pattern in its focal plane corresponding to a plane of cut out, each point of impact making a cut, - move, using the optical scanning scanner, the pattern in the cutting plan in a plurality of positions in a direction of movement D, - tilt the pattern relative to the direction of movement so that at minus two points impact of the pattern are spaced:
- a non-zero distance along a first axis parallel to the direction of displacement on the one hand, and - a non-zero distance along a second axis perpendicular to the direction of movement on the other hand.
Advantageously, the step consisting of modulating may include training of a pattern comprising at least two (in particular three) adjacent points of impact extending along of a line of the pattern, the angle between said line of the pattern and the direction of displacement being between 10 and 80, preferably between 15 and 40, and even more preferably between 19 and 30. Furthermore, the step consisting of modulate can understand the formation of a pattern having:
- a first set of at least two (notably three) points of impact arranged along a first line of the pattern, and - a second set of at least two (notably three) other points impact arranged along a second line of the pattern parallel to the first line.
The step of modulating may also include forming a pattern having at at least one other set of impact points arranged along at least one other line of pattern, parallel to the first and second lines. The step of modulating can more understand the formation of a pattern in which the points of impact of the second together are offset by a non-zero distance from the points of impact of the first set.
Alternatively, the step of modulating may include forming a reason in which each point of impact of the second set is aligned with a point of impact respective of first set along a straight line perpendicular to the direction of shift.
Advantageously, the step consisting of modulating may include training of a pattern in which the distance between two adjacent points of impact is greater than 5pm preferably greater than 10pm and even more preferably between 10 and 3 p.m.
The step of modulating may further include forming a pattern registered in a surface whose ratio between length and width is between 1 and 4, preferably between 1 and 2, and even more preferably between 1 and 1.5. Finally, the step consisting of modulating may also include the formation of a pattern having a point central impact positioned at the barycenter of the pattern.
3. Working principle We will now describe the operating principle of the device.
cutout shown at Figure 1 with reference to the destruction of a lens in the context of a operation of the cataract. It is obvious that the present invention is not limited to the operation of a cataract.
In a first step, the control unit 6:
- transmits to the shaping system 3 a first associated phase mask to a first reason for processing, - emits a control signal to the optical focusing system 5 to move the plan focusing at the level of a first cutting plane deep in the eye, - activates the movement of the optical scanning scanner 4 up to one initial position of cutting. The scanning is done in X, Y, the scanner is equipped with a mirror, which allows the scanning along each segment of the pattern movement path, and a another mirror Y, which allows you to change segments once a segment is completed. The mirrors X and Y
therefore work alternately one and the other.
When the focusing system 5 and the optical scanner 4 are in position and that the phase mask is loaded into the formatting system 3, the processing unit order 6 activates the femtosecond laser 1. This generates a LASER 11 beam which cross the shaping system 3. Shaping system 3 modulates the phase of the beam LASER The LASER beam modulated in phase 31 exits the focusing system in shape 3 and enters the optical scanner 4 which deflects the modulated LASER beam 31. The beam LA.SER modulated and deflected 41 enters the optical focusing system 5 which focuses the beam in the first cutting plane.
Each point of impact 81 of pattern 8 produces a cavitation bubble. The laser femtosecond 1 continues to emit other pulses in the form of a LA.SER beam at a cadence determined. Between each pulse the X mirror has rotated by a certain angle, this who has for consequence of moving the pattern 8 and producing new bubbles of offset cavitation compared to the previous ones, until forming a line. Thus, a first plurality of bubbles of cavitation constituting a line is formed in the cutting plane, these bubbles being arranged in accordance with the cutting pattern 8. By varying the speed of shift of the mirror and/or the rate of generation of pulses by the laser femtosecond, it is possible to vary the distance between two successive patterns.
Once this plurality of bubbles forms a complete line, the unit of command 6 deactivates the LASER 1 source, commands the stopping of the pivoting of the mirror and order the pivoting of the Y mirror of the optical scanner 4 to the next position of cut into function of the scanning step of the optical scanner 4, then commands the reboot of the pivoting of the mirror X in the opposite direction. When the optical scanner 4 is in position and the mirror X has reached its constant set speed, the unit of command 6 active at new the femtosecond laser 1. The LASER 11 beam passes through the system of implementation form 3, the optical scanner 4 and the optical focusing system 5. A
second sequel of a plurality of cavitation bubbles forms in the foreground of cutout forming a new line parallel to the previous one and juxtaposed.
These operations are repeated throughout the first cutting plane.
When the optical scanner 4 scanned the entire surface of the foreground of cutout, a first cutting zone (the shape and dimensions of which are controlled by the unit of command 6) is generated.
The control unit 6 deactivates the femtosecond laser 1 and commands:
- the translational movement of the lens(es) of the system focusing optics 5 to move the focusing plane 21 into a second cutting plane, - the rotational movement of the mirror(s) of the optical scanner 4 to a position initial cutting of the second cutting plane, - the possible loading by the formatting system 3 of another phase mask to modify the arrangement and/or size of the impact points of the pattern, etc.
The control unit 6 repeats the femtosecond laser control operations 1, from shaping system 3, the optical scanning scanner 4 and the focus 5 in the second cutting plane, and more generally in the planes of cutout successive.
At the end of these different stages, we obtain a stack of plans of cutout corresponding to the volume to be destroyed 23.
4. Conclusions Thus, the invention makes it possible to have an effective cutting tool. THE
dimensions of points of impact of the pattern being substantially equal (the shape, position and diameter of each spot are dynamically controlled by the calculated and displayed phase mask on the SLM and which can correct irregularities), cavitation bubbles that dilate biological tissues cut out will be of approximately equal size. This makes it possible to improve the quality of result obtained, with a homogeneous cutting plane, in which the tissue bridges residuals have all approximately the same size and which allow dissection by the quality practitioner 5 acceptable in view of the importance of the quality of the surface condition of the cut fabric when it concerns, for example, a cornea.
The invention has been described for operations of cutting a cornea in the domain of ophthalmological surgery, but it is obvious that it can be used for other type operation in ophthalmological surgery without departing from the scope of the invention.
For example, 10 the invention finds application in corneal refractive surgery, such as treatment ametropia, in particular myopia, hyperopia, astigmatism, in the treatment of the loss of accommodation, notably presbyopia.
The invention also finds application in the treatment of cataract with incision of the cornea, cutting of the anterior capsule of the lens, and fragmentation of 15 crystalline. Finally, more generally, the invention relates to all applications clinical or experimental studies on the cornea or lens of a human eye or animal.
Even more generally, the invention relates to the broad field of surgery to LASER and finds an advantageous application when it comes to cut out and more particularly spray human or animal soft tissues, with water content high.
20 The reader will have understood that numerous modifications can be made made to the invention described previously without materially leaving new lessons and benefits described here.
For example, in the different embodiments described above, the system focusing optics arranged downstream of the optical scanning scanner was described as 25 comprising a single module allowing:
- on the one hand to focus the modulated and deflected LASER beam, and - on the other hand to move the plane of focus in different planes of cutting.
Alternatively, the optical focusing system can be composed of two modules distinct, each ensuring one of these functions:
30 - a first module ¨ called depth positioning module -arranged upstream of the optical scanning scanner and making it possible to move the plane of focus in different cutting planes.
- a second module ¨ called concentrator module arranged downstream of the optical scanner scanning and allowing the modulated and deflected LASER beam to be focused.
Also in the different embodiments described above, the system of Described formatting was an SLM. Alternatively, the formatting system could be composed of a plurality of phase masks, each phase mask acting on the phase of the LASER beam to distribute the energy of the LASER beam by modulation of phase in a distinct pattern. Each phase mask can for example be consisting of a plate (transparent to the LASER beam) of variable thickness obtained by engraving.
In this case, the phase masks can be attached to a device routing allowing each phase mask to be moved between:
- an active position in which the phase mask cuts the path beam optics LASER, - an inactive position in which the phase mask does not extend over the path LASER beam optics The routing device is for example made up of a mobile support made of rotation around an axis of rotation parallel to the optical path of the beam LASER, the support mobile being arranged so as to allow the positioning of a mask of respective phase on the optical path of the LASER beam in order to modulate the phase of it this. However this solution requires the introduction of mechanical elements to the device (device routing) and is therefore not a preferred solution.
Furthermore, in the preceding description, the control unit issued a signal of command to the shaping system (such as a phase mask in the case where THE
shaping system is a spatial light modulator) to distribute the energy of LASER beam (by phase modulation) in at least two points of impact forming a pattern in its focal plane. Alternatively, the control unit can be programmed for emit several distinct control signals making it possible to generate different patterns one another. This allows you to modify the intensity profile of the beam LASER according to different patterns in the cutting plane, for example to improve the quality of the cutting at the contours of the cut surface in the cutting plane.
Therefore, all modifications of this type are intended to be incorporated into within the scope of the appended claims.

Claims (16)

REVEN DICATIONS 1. Apparatus for cutting human or animal tissue, the apparatus including a femtosecond laser capable of emitting a LASER beam in the form of pulses and a device treatment of the LASER beam generated by the femtosecond laser, the device treatment being arranged downstream of the femtosecond laser, in which the processing device understand :
- a shaping system positioned on the trajectory of the beam, to modulate the phase of the wavefront of the LASER beam so as to obtain a unique LASER beam modulated in phase according to a modulation instruction calculated to distribute the energy of LASER beam in at least two points of impact forming a pattern in its focal plane, the shaping system including a spatial light modulator, and a unit of control programmed to control the spatial light modulator by emission at least a control signal, each control signal inducing the display on the modulator spatial light of a phase mask forming modulation instruction, - a filter placed downstream of the shaping system to block a stray energy generated in the center of the formatting system, - an optical focusing system downstream of the shaping system, the system focusing optics comprising a concentrator module for focusing the beam LASER phase modulated in a focusing plane and a module of positioning in depth to move the plane of focus into a plurality of planes of focus cutting, - an optical scanning scanner placed between the concentrator module and the module depth positioning to move the pattern in the cutting plane by a plurality positions. 2. The apparatus according to claim 1, wherein the control unit is in further adapted to control the optical scanner to move the pattern along a path of displacement comprising at least one segment in the cutting plane. 3. The apparatus according to claim 2, wherein the control unit is programmed for control the activation of the femtosecond laser so that the distance between two positions adjacent areas of the pattern along a segment of the movement path is greater than or equal to the diameter of a point of impact of the pattern. 4. The apparatus according to any one of claims 2 or 3, in which the unit of command is adapted to control the movement of the pattern along a path of displacement comprising a plurality of segments, the distance between two segments 301038090.1 Date received/Date received 2023-05-29 adjacent to the movement path being greater than the dimension of the pattern according to one perpendicular to the direction of movement of the pattern. 5. The apparatus according to any one of claims 2 to 4, in which the unit of command is programmed to control the movement of the pattern along a road of displacement comprising a plurality of parallel segments, the distance between two neighboring segments of the path of movement being constant and lower or equal to 3N times the diameter of an impact point, where N corresponds to the number of impact points of the pattern. 6. The apparatus according to any one of claims 2 to 4, in which the unit of command is programmed to control the movement of the pattern along a road of displacement comprising a plurality of parallel segments, the distance between at least two neighboring segments being different from the distance between at least two others neighboring segments. .. 7. The apparatus according to any one of claims 2 to 6, in which the unit of command is capable of controlling the movement of the pattern along a path of moving in niche shape in the cutting plane. 8. The apparatus according to any one of claims 2 or 3, in which the unit of .. command is capable of controlling the movement of the pattern along a path of moving in spiral shape in the cutting plane. 9. The apparatus according to any one of claims 2 to 8, in which the optical scanner scanning comprises at least one optical mirror pivoting around at least two axes, unit control of the optical scanner controlling the pivoting of the mirror so as to move the pattern depending on the travel path. 10. The apparatus according to any one of claims 1 to 9, which further includes minus a Dove prism positioned between the shaping system and the optical scanner sweep. 11. The apparatus according to any one of claims 2 to 10, in which the unit of command is programmed to control the activation of the femtosecond laser, the unit of command activating the femtosecond laser when the scanning speed of the optical scanner is greater than a threshold value.
301038090.1 Date received/Date received 2023-05-29 12. The apparatus according to any one of claims 1 to 11, in which the filter includes a plate including:
- a zone opaque to LASER radiation placed in the center of the plate, And - a zone transparent to LAS.ER radiation extending to the periphery of the opaque area. 13. The apparatus according to any one of claims 1 to 12, in which the system of shaping consists of a set of phase masks, each mask acting on the phase of the LASER beam to distribute the energy of the LASER beam by modulation phase in a distinct pattern, the masks being attached to a device routing, the unit control being programmed to control the routing device in order to move each mask enters:
- an active position in which the mask cuts the optical path of the beam LASER, - an inactive position in which the mask does not extend across the path optics of LASER beam 14. The apparatus according to any one of claims 1 to 13, in which the unit of command is programmed to control the shaping system, the processing unit order being adapted to emit at least first and second signals of order :
- the first control signal inducing the modulation of the phase of the edge wave of LASER beam according to a first modulation instruction calculated for to share out the energy of the LASER beam at a plurality of first points of impact in the focal plane of the shaping system, the first points of impact constituting a first reason, - the second control signal inducing the modulation of the phase of the edge wave of LASER beam according to a second modulation instruction calculated for to share out the energy of the LASER beam at a plurality of second points of impact in the plan focal point of the shaping system, the second points of impact constituting a second pattern different from the first pattern. 15. The apparatus according to any one of claims 1 to 14, in which the instruction of modulation is a phase mask calculated using an iterative algorithm based on the Fourier transform. 16. The apparatus according to any one of claims 1 to 15, in which human tissue or animal contains a cornea or lens.
301038090.1 Date received/Date received 2023-05-29